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Paul

Model output discussion - winter proper underway

Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

Message added by Paul

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UKMO and ECM both singing from the same hymn sheet this morning at t168 with a milder flow of air moving in

ukm2.2017121700_168_lant.troplant_prp_fcst.gentracker.thumb.png.4917edbcf8ac3a35de19921db03bdc8c.pngecm2.2017121700_168_lant.troplant_prp_fcst.gentracker.thumb.png.f725ed2cce7ad32e0b35b3b19247965e.png

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2 hours ago, nick sussex said:

Our positive trend of yesterday has hit the buffers this morning!

The upstream pattern doesn’t re-amplify and a lobe of the PV ne of Scandi  runs west re-invigorating the PV near Greenland .

The cold extension is looking  ropy this morning but we’ll have to wait to see what tonight brings.

There has been a pattern recently of flatter 00hrs runs and more amplified 12 hrs so let’s hope that continues.

I suspect we will see varying output from the models in the days ahead, some will ramp up the atlantic due to the foreseen changes you mention, whereas others will show a much weaker attempt - my own hunch is any atlantic onslaught will be weak and watered down, and longer terms heights to the NE will be the growing theme - may take a bit of time, period of interest exactly around christmas, a white cold New Year could be on the cards.

 

 

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Would be nice to see some info on the 0z, I am a never poster as I have no clue what I am looking for and usually read this!! :-)

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2 minutes ago, jessandjon said:

Would be nice to see some info on the 0z, I am a never poster as I have no clue what I am looking for and usually read this!! :-)

To be honest, the models look dreadful this morning for the medium to long term. Why have they all gone so flat I wonder. 

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5 minutes ago, blizzard81 said:

To be honest, the models look dreadful this morning for the medium to long term. Why have they all gone so flat I wonder. 

Yes they do...

The vortex looks to be heading back to its perch very soon...

All eyes to the strat soon looking for hope of a warming

 

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Just now, blizzard81 said:

To be honest, the models look dreadful this morning for the medium to long term. Why have they all gone so flat I wonder. 

Because as Tamara and GP pointed out the other day there will be a transition period from the end of the current Atlantic ridge driven cold spell to another cold spell come xmas/new year driven by hieght rises to our north and northeast. This was always on the cards and it is no surprise to see it in the modelling.

Edited by Broadmayne blizzard

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4 minutes ago, Broadmayne blizzard said:

Because as Tamara and GP pointed out the other day there will be a transition period from the end of the current Atlantic ridge driven cold spell to another cold spell come xmas/new year driven by hieght rises to our north and northeast. This was always on the cards and it is no surprise to see it in the modelling.

Yes, but the question is whether those atmospheric drivers are still present.

Today's output is about as flat and vile as we've seen for a couple of years, going back to December 15's horror show.

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Just now, bluearmy said:

Five clusters on the extended eps tells me that the modelling is waiting to decide where it's going 

also, it's two weeks since we saw the mid Atlantic/greeny high and nw euro low anomoly raise som eyebrows in here

this morning we have this chart for Xmas - not a bad place to be methinks as it won't be exactly like this and adjustments in coldies favour could be very festive indeed

IMG_0675.thumb.PNG.e0f9916f10404fcaef4a6ca44a04fb29.PNG

 

Bluearmy, what are you doing on here, aren't you buried in mountains of snow ;)

With no snow for amusement, I also had a look at the clusters today - always happier when they come up with several!

The Scandi high for 19/20 looks shaky but not dropped completely in the ensembles, the control run has a cluster that looks like one might develop.

As BA mentions, Christmas Day now in range of the extended ensembles, on the face of it a mild SWly couldn't be discounted, but there are clusters that do provide a way to a white Christmas, particularly those that get the trough a bit further south.

ec-ens_nat_z500scenarios_2017121000_360.

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The picture in six days time as seen by the main models:

UKMO   image.thumb.gif.3f7b6ba10579ceb89eeda00a23950599.gif  image.thumb.gif.5f2fdcee12cf790dfaaf58b4847082cd.gif

ECM      image.thumb.gif.b138345a4cd1d96dd991157ce614d39d.gif  image.thumb.gif.71ea3268cfc2380035ddfd7dd2f149ca.gif

GFS       image.thumb.png.ed316f9d2f04298ab7390454638b8ac7.png  image.thumb.png.bc9d29ded0c644c600ed129eb500ba19.png

GEM      image.thumb.png.6b61ad7b3f23c43ce409ab235011b4ef.png  image.thumb.png.836a167a98942e45a21fc0e97a1bb59c.png

All telling much the same story - colder infulences have not yet disappeared completely but later charts show the Azores high  flattens out and allows a westerly flow from the Atlantic in the following days.  This would result in warmer, moist air over the UK and probably windier conditions - no snowy potential at all.  We can only wait to see if further blocking begins to set up before Christmas but in the meantime we can still enjoy our wintery spell for today and probably tomorrow at least. 

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6 minutes ago, Broadmayne blizzard said:

Because as Tamara and GP pointed out the other day there will be a transition period from the end of the current Atlantic ridge driven cold spell to another cold spell come xmas/new year driven by hieght rises to our north and northeast. This was always on the cards and it is no surprise to see it in the modelling.

I have total respect for GP and Tamara. Im not sure they have said there will be a Scandi high only it is a distinct possibility given what is expected in the pacific and subsequent PV movement west. There also has to be the possibilty on what we see in the 06z Op and have a strong PV to our North. If GP or Tamara could forcast that far out for our little corner and nail it everytime they would both be very rich people. Saying this i hope this is of the ones they Nail as the 06z op is total pants!

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Och weel. Today's 06Z is a tad more mobile than yesterday's runs...Has yet another of Piers Corbyn's solar filaments gone AWOL?:D

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Just now, Nicholas B said:

I have total respect for GP and Tamara. Im not sure they have said there will be a Scandi high only it is a distinct possibility given what is expected in the pacific and subsequent PV movement west. There also has to be the possibilty on what we see in the 06z Op and have a strong PV to our North. If GP or Tamara could forcast that far out for our little corner and nail it everytime they would both be very rich people. Saying this i hope this is of the ones they Nail as the 06z op is total pants!

Of course Tamara and GP are not the weather gods but they along with a couple of others are nevertheless our global drivers experts and if they are suggesting the current set up even allowing for a flatter transition period is likely to lead to hieght rises to our northeast (which i would equate to a scandi or arctic ridge) then thats good enough for me. 

I think Blue and MWB take the right line here by summarising the whole forecast runs not just the single deterministic operational run. 

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55 minutes ago, Broadmayne blizzard said:

Because as Tamara and GP pointed out the other day there will be a transition period from the end of the current Atlantic ridge driven cold spell to another cold spell come xmas/new year driven by hieght rises to our north and northeast. This was always on the cards and it is no surprise to see it in the modelling.

Posters putting to much faith in what Tamara and GP have to say will lead to tears time and again. Some posters have very short memories. Having said that they may be right and they may be wrong.  Events happening in the strat now that it is properly coupled with the trop will dictate where the weather will be heading in the next couple of weeks. This reminds me very much of 12/13 so I would not be surprised to see a more mobile pattern unfortunately over the next couple of weeks similar to Dec 12 when the strat was undergoing a warming. It may not be till late Dec or early Jan before we see a switch back to a much colder and blocked pattern setting up again. I really hope I am wrong though.

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Just now, comet said:

Posters putting to much faith in what Tamara and GP have to say will lead to tears time and again. Some posters have very short memories. Having said that they may be right and they may be wrong.  Events happening in the strat now that it is properly coupled with the trop will dictate where the weather will be heading in the next couple of weeks. This reminds me very much of 12/13 so I would not be surprised to see a more mobile pattern unfortunately over the next couple of weeks similar to Dec 12 when the strat was undergoing a warming. It may not be till late Dec or early Jan before we see a switch back to a much colder and blocked pattern setting up again. I really hope I am wrong though.

Hi Comet the final five lines of your post are exactly what Tamara and GP have been suggesting.

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The GEFS 6z mean shows a period of zonal atlantic mobility (positive NAO) for week 2..the run up to and including christmas with spells of milder wet and windy weather, especially across the n / nw  with the s / se having some decent dry intervals inbetween the more unsettled conditions..something of a n/s or nw/se split for a while before it becomes progressively more unsettled further south too.

21_246_850tmp.png

21_270_850tmp.png

21_318_500mb.png

21_342_500mb.png

21_366_500mb.png

Edited by Frosty.

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9 minutes ago, chrisbell-nottheweatherman said:

Seems likely that we are going to see a longer spell of mild zonality despite background signals, then?

Not necessarily! The models will not be picking up on these background signals for a while yet, perhaps for another another 5-7 days in my view. 

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15 minutes ago, chrisbell-nottheweatherman said:

Seems likely that we are going to see a longer spell of mild zonality despite background signals, then?

To be fair, the GEFS mean has been showing this for a while but it's been generally ignored / overlooked in the cold frenzy.

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The models show we have one more spell of Atlantic ridging at the end of the coming week which will bring us a rather cold nw.and then the upstream change looks like kicking in and we see a more typical westerly setup as the Canadian vortex extends east.

 gensnh-21-1-228.pngEDH1-240.GIF?10-12

The disappearance of the Alaskan ridge translating to a flattening out of the Atlantic jet beyond day 7.

Short term we have still have a couple of cold days with some sharp frosts especially over lying snow,then a bit of a warm up mid-week-fax T84hrs

fax84s.gif

with that nw flow following behind.

Further on and looking at the day 15 eps shows a resurgent upstream ridge over the west coast of NA,a Hudson bay tough and still a flat looking Atlantic/Azores high with a weak downstream Scandinavian trough.This the latest gefs take on it at the same time.

gensnh-21-5-360.png

 

Pretty good agreement within the 2 ens suites for the placement of the overall 500hPa ht anomalies. A more typical westerly outlook is beckoning with temperatures closer to average in week 2.

Whether the upstream developments will work into the Atlantic pattern beyond this period remains to be seen but with those +ve ht anomalies across the Arctic there is certainly room for optimism if it's further cold you are looking for. 

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3 minutes ago, Frosty. said:

To be fair, the GEFS mean has been showing this for a while but it's been generally ignored / overlooked in the cold frenzy.

ECM ens too Karl.:)

Nothing overly mild generally speaking but something more typical in week 2.

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1 minute ago, phil nw. said:

ECM ens too Karl.:)

Nothing overly mild generally speaking but something more typical in week 2.

Indeed phil, as you say, something more typical. Although generally milder and Atlantic driven during week 2 it doesn't preclude some short lived colder, brighter showery interludes with wintry showers and night frosts which might coincide with christmas.:)

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Picked this put from the GFS... seems to be a bit of a recurrent pattern. With ridging in the atlantic as cold air spills from the north. I know people are stating mild zonal weather for christmas. But given the amount of snow we have had, I think its too close to call personally. Not convinced about polar vortex strengthening either. 

h850t850eu.png

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